Rethinking Measurement Standards of Autism Symptomology in Adolescents with Fragile X Syndrome.
Heather Fielding-Gebhardt, Shelley L Bredin-Oja, Steven F Warren and 1 others
PMID 33550495WHAT IT FOUND
Adolescents with Fragile X Syndrome receive autism diagnoses at very different rates depending on the test used.
The ADOS-2 identified autism in 71% of participants, while the CARS2-ST identified it in only 38%. Discrepancies occurred because the ADOS-2 often flagged social communication deficits without requiring evidence of restricted or repetitive behaviors.
Key findings
01The ADOS-2 classified 71% of the sample as meeting autism or autism spectrum criteria, whereas the CARS2-ST classified only 38% as having mild-to-moderate or severe autism symptoms.
02Participants classified as having autism on the ADOS-2 but not the CARS2-ST showed significant social affect impairments but did not demonstrate elevated restricted and repetitive behaviors during the assessment.
03A novel approach using Vineland Adaptive Behavior Scales maladaptive items and a parent interview question aligned more closely with the CARS2-ST than the ADOS-2, suggesting it may better capture the dual-domain DSM-5 criteria.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The sample size was small (45 participants) and not equally divided by sex (35 males, 10 females), which limits generalizability given that FXS presentation varies by sex. The sample was a convenience sample with limited racial and ethnic diversity and higher socioeconomic status. The same research team administered all assessments, which may have influenced scoring consistency between the ADOS-2 and CARS2-ST. The study did not use the ADI-R, a standard parent-report diagnostic tool, for comparison. The novel measurement approach requires further validation across different populations and age groups.
Declared interests
No specific funding sources or conflict of interest declarations were provided in the supplied text.
The easy way to misread this
Do not interpret the high ADOS-2 classification rate as definitive evidence that most adolescents with FXS have co-occurring autism. The study suggests this rate may be inflated because the ADOS-2 can classify autism based on social communication deficits alone, without requiring the restricted and repetitive behaviors mandated by DSM-5 criteria.